Fabrication method of semiconductor integrated circuit device

ABSTRACT

Productivity is to be improved in assembling a semiconductor integrated circuit device. A matrix substrate is provided and semiconductor chips are disposed on a first heating stage, then the matrix substrate is disposed above the semiconductor chips on the first heating stage, subsequently the semiconductor chips and the matrix substrate are bonded to each other temporarily by thermocompression bonding while heating the chips directly by the first heating stage, thereafter the temporarily bonded matrix substrate is disposed on a second heating stage adjacent to the first heating stage, and then on the second heating stage the semiconductor chips are thermocompression-bonded to the matrix substrate while being heated directly by the second heating stage.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority from Japanese Patent application JP 2003-327046, filed on Sep. 19, 2003, the content of which is hereby incorporated by reference into this application. This application is a Divisional application of prior application Ser. No. 10/901,999, filed Jul. 30, 2004, the contents of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to a method of fabricating a semiconductor integrated circuit device, and, more particularly, to a technique for use in the fabrication of a semiconductor integrated circuit device wherein a semiconductor chip is bonded to a substrate.

In the conventional way of providing bonding between a substrate and silicon chips, the substrate is disposed on a substrate rest (stage); then, plural silicon chips are arranged on the substrate; and heat is conducted to the silicon chips through the substrate by means of a heating cartridge provided on the substrate rest (see, for example, Patent Literature 1 and Patent Literature 2, which is a European patent application corresponding to Patent Literature 1).

[Patent Literature 1]

Japanese Unexamined Patent Publication No. 2002-534799

(FIG. 2)

[Patent Literature 2]

EP 1030349A2 (FIG. 2)

SUMMARY OF THE INVENTION

To effect bonding between a wiring substrate and semiconductor chips by flip-chip connection, the semiconductor chips are picked up from a semiconductor wafer; then they are disposed on the substrate in such a manner that their main surfaces face toward the substrate; and, thereafter, the chips and the substrate are bonded together by thermocompression bonding, for example.

Therefore, a mechanism for conveying the semiconductor chips onto the wiring substrate is disposed above the substrate. On the other hand, it is difficult to dispose a heating mechanism above the wiring substrate because of the fact that the conveyance mechanism is disposed above the substrate, and, therefore, the heating mechanism typically is embedded into a stage located below the wiring substrate.

In this structure, if heating is conducted from the stage side, the chip-substrate bonding portions are heated through the wiring substrate, so that the temperature of the bonding portions does not rise to a satisfactory extent, thus causing the problem of imperfect bonding. On the other hand, if the heating temperature is set high to obtain a sufficient temperature of the bonding portions, various problems arise, such as warping of the wiring substrate and peel-off of the compression-bonded portions, or an inconvenience occurs in a later step.

It is an object of the present invention to provide a method of fabricating a semiconductor integrated circuit device that is capable of improving the productivity.

It is another object of the present invention to provide a method of fabricating a semiconductor integrated circuit device that capable of stabilizing the chip bonding quality.

The above and other objects and novel features of the present invention will become apparent from the following description and the accompanying drawings.

Typical modes of the present invention as disclosed herein will be outlined below.

In accordance with the present invention, plural semiconductor chips are arranged in such a manner that respective main surfaces face upward, and then a substrate disposed above the plural semiconductor chips and the semiconductor chips are bonded together by thermocompression bonding.

Other modes of the present invention will be described below paragraph by paragraph.

1. A method of fabricating a semiconductor integrated circuit device, comprises the steps of:

-   (a) providing a substrate; -   (b) disposing a plurality of semiconductor chips on a stage in such     manner that respective main surfaces face upward; -   (c) disposing the substrate above the plural semiconductor chips;     and -   (d) bonding the plural semiconductor chips all together to the     substrate by thermocompression bonding (compression bonding or     adhesion under heating).

2. A method according to the above paragraph 1, wherein an organic substrate is used as the substrate.

3. A method of fabricating a semiconductor integrated circuit device, comprises the steps of:

-   (a) providing a substrate; -   (b) disposing a plurality of semiconductor chips on a heating stage; -   (c) disposing the substrate above the plural semiconductor chips;     and -   (d) pressurizing the plural semiconductor chips correspondingly by     plural pressure blocks while heating the semiconductor chips     directly by the heating stage, the plural pressure blocks each being     supported for independent movement in corresponding relation to the     semiconductor chips, thereby thermocompression-bonding the     semiconductor chips all together to the substrate.

4. A method according to the above paragraph 3, wherein at the time of pinching and compression-bonding the substrate and the semiconductor chips by the use of plural pressure blocks and the heating stage, air at a first pressure is applied to the plural pressure blocks prior to compression-bonding; then, in this state, the pressure blocks are brought into contact with the substrate, or the semiconductor chips are brought into contact with the heating stage; and, thereafter, air at a second pressure higher than the first pressure is applied to the pressure blocks to effect thermocompression bonding.

5. A method according to the above paragraph 3, wherein the pressure applied to the pressure blocks in step (d) is raised gradually from a low pressure and a point of change of a load imposed on a load change detecting means is detected by the load change detecting means to determine the magnitude of the pressure applied to the plural semiconductor chips, the load change detecting means being connected to support block portions for supporting the plural pressure blocks.

6. A method according to the above paragraph 3, wherein, prior to the step (b), the plural pressure blocks and the heating stage are brought into contact with each other, and then, in this state, the pressure applied to the pressure blocks is raised gradually from a low pressure, and a point of change of a load imposed on a load change detecting means is detected by the load change detecting means, the load change detecting means being connected to support block portions for supporting the plural pressure blocks to determine the magnitude of a set value of the pressure applied to the pressure blocks at the time of thermocompression-bonding the plural semiconductor chips disposed on the heating stage to the substrate.

7. A method according to the above paragraph 3, wherein the plural pressure blocks are pressurized by air through a single sheet-like elastic film.

8. A method of fabricating a semiconductor integrated circuit device, comprises the steps of:

-   (a) providing a substrate; -   (b) disposing a plurality of semiconductor chips on a first heating     stage; -   (c) disposing the substrate above the semiconductor chips disposed     on the first heating stage and thereafter bonding the semiconductor     chips and the substrate to each other temporarily by     thermocompression bonding while heating the semiconductor chips     directly by the first heating stage; -   (d) after the step (c), disposing the temporarily bonded     semiconductor chips and substrate on a second heating stage adjacent     to the first heating stage; and -   (e) pressurizing the semiconductor chips over the second heating     stage for a longer time than in the first heating stage while     heating the semiconductor chips directly by the second heating stage     to effect a main bonding of the semiconductor chips and the     substrate by thermocompression bonding.

9. A method according to the above paragraph 8, wherein the plural semiconductor chips are arranged on the second heating stage and the plural semiconductor chips are all together subjected to a main bonding to the substrate by thermocompression bonding while being heated directly by the second heating stage.

10. A method according to the above paragraph 8, wherein, prior to the step (b), a high pressure is applied to a plurality of pressure blocks each of which are supported for independent movement in corresponding relation to plural semiconductor chips, the high pressure being high to such an extent that the pressure blocks are not pushed up, then in this state the plural pressure blocks and the second heating stage are brought into contact with each other, and a point of change of a load imposed on a load change detecting means is detected by the load change detecting means to determine a landing height of the plural pressure blocks, the load change detecting means being connected to support block portions for supporting the pressure blocks.

11. A method according to the above paragraph 8, wherein support block portions for supporting a plurality of pressure blocks each of which are supported for independent movement in corresponding relation to the plural semiconductor chips are mounted to a body portion removably.

12. A method according to the above paragraph 11, wherein the support block portions are mounted to the body portion removably through a spacer.

13. A method according to the above paragraph 8, wherein a plurality of small-sized stages smaller than a back surface of each of the semiconductor chips are provided on the second heating stage, and the semiconductor chips are disposed on the plural small-sized stages.

14. A method according to the above paragraph 8, wherein a plurality of suction systems which are open to the chips-disposed side of the second heating stage are provided in the second heating stage, and at the time of thermocompression bonding of the semiconductor chips and the substrate, dust particles adhered to the chips-disposed side are removed by suction through suction systems provided in the second heating stage.

15. A method of fabricating a semiconductor integrated circuit device, comprises the steps of:

-   (a) providing a substrate; -   (b) disposing a semiconductor chip on a heating stage; -   (c) disposing the substrate above the semiconductor chip; and -   (d) heating the semiconductor chip by the heating stage and heating     the substrate by a heating means disposed above the substrate in     such a manner that the heating temperature on the semiconductor chip     side is higher than that on the substrate side, and bonding the     semiconductor chip and the substrate to each other by     thermocompression bonding.

16. A method according to the above paragraph 15, wherein the substrate is heated at a temperature of not higher than 150° C. by the heating means.

17. A method according to the above paragraph 15, wherein the substrate is heated at a temperature of not higher than 100° C. by the heating means.

18. A method according to the above paragraph 15, wherein the substrate is heated at a temperature of not higher than 50° C. by the heating means.

19. A method according to the above paragraph 15, wherein the substrate is heated at a normal temperature by the heating means.

20. A method according to the above paragraph 15, wherein an organic substrate is used as the substrate.

Still other modes of the present invention will be outlined below paragraph by paragraph.

1. A method of fabricating a semiconductor integrated circuit device, comprises the steps of:

-   (a) providing a matrix substrate on which a plurality of device     areas each for the semiconductor integrated circuit device are     formed in a matrix array; -   (b) disposing a plurality of semiconductor chips onto a stage in     such a manner that respective main surfaces face upward; -   (c) disposing the matrix substrate above the plural semiconductor     chips; and -   (d) bonding the semiconductor chips to the matrix substrate by     thermocompression bonding simultaneously in one or plural rows in     the width direction of the matrix-arrayed device areas on the matrix     substrate.

2. A method of fabricating a semiconductor integrated circuit device, comprises the steps of:

-   (a) providing a matrix substrate on which a plurality of device     areas each for the semiconductor integrated circuit device are     formed in a matrix array; -   (b) disposing a plurality of semiconductor chips onto a heating     stage; -   (c) disposing the matrix substrate above the plural semiconductor     chips; and -   (d) pressurizing the plural semiconductor chips corresponding     respectively to a plurality of pressure blocks while heating the     semiconductor chips directly by the heating stage, the plural     pressure blocks each being supported for independent movement in     corresponding relation to the semiconductor chips to bond the     semiconductor chips to the matrix substrate by thermocompression     bonding simultaneously in one or plural rows in the width direction     of the matrix-arrayed device areas on the matrix substrate.

Still other modes of the present invention will be outlined below paragraph by paragraph.

3. A semiconductor device fabricating apparatus comprises:

-   (a) a heating stage which permits a plurality of semiconductor chips     to be disposed thereon; -   (b) a support block portion having a plurality of pressure blocks     and a space for the supply of air to pressurize the plural pressure     blocks, the pressure blocks each being supported for independent     movement in corresponding relation to the plural semiconductor     chips; -   (c) an air introducing portion for introducing air into the space of     the support block portion; and -   (d) a load change detecting means connected to the support block     portion to detect a point of change of a load.

4. A semiconductor device fabricating apparatus comprises:

-   (a) a heating stage which permits a plurality of semiconductor chips     to be disposed thereon; -   (b) a support block portion mounted removably to a body portion and     having a plurality of pressure blocks and a space for the supply of     air to pressurize the plural pressure blocks; -   (c) an air introducing portion for introducing air into the space of     the support block portion; and -   (d) a load change detecting means connected to the support block     portion to detect a point of change of a load.

5. A semiconductor device fabricating apparatus comprises:

-   (a) a heating stage having a plurality of small-sized stages, the     small-sized stages permitting a plurality of semiconductor chips to     be respectively disposed thereon and each being smaller than a back     surface of each of the semiconductor chips; -   (b) a support block portion having a plurality of pressure blocks     and a space for the supply of air to pressurize the plural pressure     blocks, the pressure blocks each being supported for independent     movement in corresponding relation to the plural semiconductor     chips; -   (c) an air introducing portion for introducing air into the space of     the support block portion; and -   (d) a load change detecting means connected to the support block     portion to detect a point of change of a load.

6. A semiconductor device fabricating apparatus comprises:

-   (a) a heating stage which permits a plurality of semiconductor chips     to be disposed thereon; -   (b) a support block portion having a plurality of pressure blocks     and a space for the supply of air to pressurize the plural pressure     blocks, the pressure blocks each being supported for independent     movement in corresponding relation to the plural semiconductor     chips; -   (c) a sheet-like elastic film disposed within the support block     portion so as to be in close contact with the plural pressure     blocks; -   (d) an air introducing portion for introducing air into the space of     the support block portion; and -   (e) a load change detecting means connected to the support block     portion to detect a point of change of a load.

The following is a brief description of effects obtained by typical modes of the present invention as disclosed herein.

Die bonding is carried out in a divided manner into a temporary bonding and a main bonding with use of first and second heating stages. The temporary bonding is carried out in a short time using the first heating stage, and, subsequently, the main bonding is carried out for plural semiconductor chips simultaneously using the second heating stage, whereby it is possible to shorten the bonding time. Consequently, it is possible to improve the throughput of die bonding and, hence, to improve the productivity thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an example of the structure on an external terminal side of a semiconductor integrated circuit device embodying the present invention;

FIG. 2 is a perspective view showing, through a sealing member, an example of the chip-side internal structure of the semiconductor integrated circuit device illustrated in FIG. 1;

FIG. 3 is a sectional view showing a structural example of the semiconductor integrated circuit device illustrated in FIG. 1;

FIG. 4 is a fabrication process flow chart showing an example of an assembling procedure for the semiconductor integrated circuit device illustrated in FIG. 1;

FIG. 5 is a plan view showing an example of the structure on a surface side of a wiring substrate in the assembling procedure illustrated in FIG. 4;

FIG. 6 is a plan view showing an example of the structure on a back surface side of the wiring substrate in the assembling procedure illustrated in FIG. 4;

FIG. 7 is a plan view showing an example of the structure on the back surface side of the wiring substrate after die bonding in the assembling procedure illustrated in FIG. 4;

FIG. 8 is a diagrammatic plan view showing an example of the structure of a semiconductor device fabricating apparatus embodying the present invention;

FIG. 9 is a sectional view showing a structural example of principal portions of the semiconductor device fabricating apparatus illustrated in FIG. 8;

FIG. 10 is a perspective view showing a structural example of principal portions of the semiconductor device fabricating apparatus illustrated in FIG. 8;

FIG. 11 is a sectional view showing a structural example of a second heating stage-side principal portion of the principal portions illustrated in FIG. 10;

FIG. 12 is a sectional view showing an example of the operation flow at the time of a low load landing of the principal portion illustrated in FIG. 11;

FIG. 13 is a sectional view showing a modified example of the operation flow at the time of a low load landing of the principal portion illustrated in FIG. 11;

FIG. 14 is a sectional view showing a structural example in landing detection of the principal portion illustrated in FIG. 11;

FIG. 15 is a sectional view showing a structural example in load setting of the principal portion illustrated in FIG. 11;

FIG. 16 is a sectional view showing a structural example in type switching of the principal portion illustrated in FIG. 11;

FIG. 17 is a sectional view showing an example of a closely contacted state of an elastic member in the principal portion illustrated in FIG. 11;

FIG. 18 is a sectional view showing an example of a dust particle sucking state in the principal portion illustrated in FIG. 11;

FIG. 19 is a perspective view showing a structural example in a mounted state of a support block portion in the principal portion illustrated in FIG. 11;

FIG. 20 is a perspective view showing an example of a method for mounting the support block portion illustrated in FIG. 19;

FIG. 21 is a developed perspective view showing a structural example of internal parts of the support block portion illustrated in FIG. 20;

FIG. 22 is a sectional view showing a structural example of the support block portion illustrated in FIG. 20;

FIG. 23 is a sectional view showing various modified structural examples of the support block portion illustrated in FIG. 22; and

FIG. 24 is a sectional view showing the structure of a semiconductor integrated circuit device according to a modification in the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the following description of the embodiments, as to the same or similar portions, repeated explanations thereof will be omitted in principle except where required.

Where required for convenience' sake, the subject matter of the invention will be described in a divided manner into plural sections or embodiments, but unless otherwise mentioned, they are not unrelated to each other, but are to be considered in a relation such that one is a modification, a description of details, or a supplementary explanation, of part or the whole of the other.

In the following description of the embodiments, when reference is made to a number of elements (including a number, numerical value, quantity, and range), no limitation is made to the number referred to, but values above and below the number referred to will do as well, unless otherwise mentioned and except in the case where it is basically evident that a limitation is made to the number referred to.

When reference is made to a component of a member (e.g., a member X comprising A), the inclusion of other components is not excluded, unless otherwise mentioned or except in the case where a negative answer is evident. This is also true of an ambient gas and the like.

The term “semiconductor integrated circuit device (simply semiconductor chip)” as referred to herein is meant to include not only one fabricated on a silicon semiconductor chip, but also one fabricated on an SOI substrate and those fabricated on other substrates, such as TFT liquid crystal, unless otherwise mentioned.

Likewise, the term “integrated circuit chip” as referred to herein is meant to include not only a silicon single crystal chip”, but also an SOI substrate, a GaAs substrate, and a generally square or rectangular integrated circuit substrate for the fabrication of TFT liquid crystal, unless otherwise mentioned.

The present invention will be described in detail hereinunder with reference to the accompanying drawings. In all of the drawings, members having the same functions are identified by the same reference numerals, and repeated explanations thereof will be omitted.

Embodiments

A semiconductor integrated circuit device embodying the present invention is in the form of a resin-sealed semiconductor package wherein an organic substrate 3 serving as a wiring substrate and a semiconductor chip 1 are bonded together. In this embodiment, reference will be made as an example to a BOC (Board On Chip) 7, as shown in FIG. 1.

A description will now be given of the structure of the BOC 7 shown in FIGS. 1 to 3. The BOC 7 comprises an organic substrate 3. The organic substrate 3 has an elongated aperture 3 e formed centrally and longitudinally of one face of the organic substrate. Bump lands 3 f are formed in two rows on each of both sides of the aperture 3 e, plural bonding electrodes 3 c are formed in proximity to the aperture 3 e, and wires 3 d are provided for connecting the bump lands 3 f and the bonding electrodes 3 c electrically with each other.

A semiconductor chip 1 is bonded to the opposite face of the organic substrate 3 through die bonding tapes 2, and plural wires 4 are used for connecting pads (surface electrodes) 1 a on the semiconductor chip 1 and corresponding bonding electrodes 3 c with each other electrically. A sealing member 6 seals the semiconductor chip 1 and the plural wires 4 with resin, and plural solder balls 5 are provided external terminals formed on the bump lands 3 f, respectively.

The semiconductor chip 1 is formed of silicon, for example, and an integrated circuit is incorporated therein. The semiconductor chip 1 is bonded to the organic substrate 3 through die bonding tapes 2 (also called elastomer, die attaching tapes, or die bonding films) in such a manner that a main surface (first main surface) 1 b thereof faces the substrate.

More specifically, the organic substrate 3 is disposed on the main surface 1 b of the semiconductor chip 1 through die bonding tapes 2; and, as shown in FIG. 3, the pads 1 a on the semiconductor chip 1 and corresponding bonding electrodes 3 c shown in FIG. 1 are connected with each other through the aperture 3 e formed in the organic substrate 3 and through the wires 4. For example, the wires 4 are gold wires.

The organic substrate 3 is an organic wiring substrate, which comprises a base formed of an organic material, as well as wires 3 d formed of copper, for example, and bump lands 3 f and bonding electrodes 3 c, which are all formed on the base. The wires 3 d are covered, insulated and protected with a solder resist film, which is an organic insulating film (organic layer). The sealing member 6 is an epoxy resin for example.

The following description is directed to the manner of assembling the BOC 7.

First, as shown in step S1 in FIG. 4, and also shown in FIG. 5, a matrix substrate 3 g is provided having device areas 3 h representing plural areas of BOCs 7 arranged in matrix form. That is, the matrix substrate 3 g has plural organic substrates 3. FIG. 5 illustrates the structure of a surface 3 a side of the matrix substrate 3 g. In each device area 3 h, plural wires 3 d are formed on both sides of a central aperture 3 e.

FIG. 6 illustrates the structure of a back surface 3 b side of the matrix substrate 3 g. Die bonding tapes 2 such as an elastomer are affixed to both sides of the central aperture 3 e. The die bonding tapes 2, or elastomer, may be replaced by an adhesive such as a thermoplastic resin. It is optional whether the adhesive is to be thermoplastic or thermosetting. For example, it is formed of a material having a single-layer structure. In the case where the adhesive is a coating material, the coating material is applied in a semi-hardened state.

Thereafter, as shown in step S2 in FIG. 4, and also shown in FIG. 7, die bonding is performed to bond semiconductor chips 1 through die bonding tapes 2, respectively, to device areas 3 h formed on the back surface 3 b of the matrix substrate 3 g. At this time, both are bonded together in such a manner that the main surface 1 b of each semiconductor chip 1 is bonded to the die bonding tapes 2, and the pads 1 a in the semiconductor chip 1 are positioned within the aperture 3 e formed in each device area 3 h on the matrix substrate 3 g.

Subsequently, wire bonding is performed in step S3. More specifically, as shown in FIG. 3, the pads 1 a in each semiconductor chip 1 and bonding electrodes 3 c (see FIG. 1) in the corresponding device area 3 h on the matrix substrate 3 g are connected together through wires 4.

Thereafter, resin molding is performed in step S4. In this step, the plural device areas 3 h on the matrix substrate 3 g are subjected all together to resin molding.

Subsequently, balls are mounted in step S5. In this step, solder balls 5 serving as external terminals are mounted respectively on bump lands 3 f in each device area 3 h on the matrix substrate 3 g.

Thereafter, in step S6, dicing is performed to divide the substrate into individual packages. More specifically, the matrix substrate 3 g and the sealing member 6 are diced into individual device areas 3 h. In this way, assembling of the BOC 7 is completed.

Next, in connection with a method of fabricating the semiconductor integrated circuit device (BOC 7) embodying the present invention, a detailed description will be given below about the die bonding used in the assembling of the BOC 7.

Reference will first be made to the main construction of a chip mounter (semiconductor fabricating apparatus) 8 used in the die bonding (chip mounting) step.

The chip mounter 8 shown in FIG. 8 comprises a first compression bonding unit 9 for compression-bonding the matrix substrate 3 g and the semiconductor chips 1 to each other temporarily (temporary bonding), a second compression bonding unit 10 for main compression bonding (main bonding) after the temporary bonding, a stocker 11 for storage of the matrix substrate 3 g before compression bonding of the chips, a handler 13 for taking out the matrix substrate 3 g from the stocker 11 and placing it on guide rails 12, a prebaking unit 14 for prebaking the matrix substrate 3 g, a load port 15 for storing a diced semiconductor wafer, a transfer robot 16 for taking out the semiconductor wafer from the load port 15 and transferring it onto a wafer stage 17, a pickup unit 18 for picking up the semiconductor chips 1 from the semiconductor wafer positioned on the wafer stage 17 and conveying them to the first compression bonding unit 9, and a product unloader 19 for storing the matrix substrate 3 g after the main compression bonding of the semiconductor chips 1.

As shown in FIGS. 9 and 10, a first head 9 a for the application of pressure and a heating stage (first stage) 9 b capable of carrying the semiconductor chips 1 thereon are provided in the first compression bonding unit 9, with a heater 9 c operating as heating means being incorporated in each of the first head 9 a and the first heating stage 9 b. The first head 9 a is provided at a front end thereof with a support block portion 9 f having a pressure block 9 g. The support block portion 9 f is attached to a block body portion 9 d, which in turn is connected to an inclination adjusting mechanism 9 e. The first heating stage 9 b is mounted to an XY stage 9 h.

In the first compression bonding unit 9, as shown in FIG. 9, positioning of the semiconductor chips 1 and temporary compression bonding between the semiconductor chips 1 and the matrix substrate 3 g are carried out as a first step. The temporary bonding involves bonding to such an extent that the semiconductor chips 1 do not peel. In the first compression bonding unit 9, the chips are subjected to thermocompression bonding one by one by the first head 9 a.

In the thermocompression bonding, the semiconductor chips 1 are heated directly by the first heating stage 9 b without interposition of the matrix substrate 3 g; and, at the same time, the bonding portions between the semiconductor chips 1 and the matrix substrate 3 g are heated through the matrix substrate 3 g by the heater 9 c incorporated in the block body portion 9 d, which is disposed above the matrix substrate 3 g. The pressurizing time for one semiconductor chip 1 in the first compression bonding unit 9 is, for example, 0.1 second or so.

On the other hand, in the second compression bonding unit 10, a second head 10 a for the application of pressure and a second heating stage (second stage) 10 b capable of carrying the semiconductor chips 1 thereon are provided, and a heater 10 c operating as heating means is incorporated in each of the second head 10 a and the second heating stage 10 b. The second head 10 a is provided at a front end thereof with a support block portion 10 m having plural pressure blocks 10 n. The support block portion 10 m is attached removably to a block body portion (body portion) 10 d, which in turn is connected to an inclination adjusting mechanism 10 i.

The plural pressure blocks 10 n are disposed in a space 10 p which is defined in the interior by the support block portion 10 m and the block body portion 10 d. In the space 10 p, the pressure blocks 10 n are supported within the support block portion 10 m in a state in which they are pressed by a single sheet-like elastic film 10 t so as to be independently movable in the vertical direction.

An air supply system 10 q, providing a passage of air to be fed to the space 10 p, is formed in the block body portion 10 d.

In the second compression bonding unit 10, the semiconductor chips 1, having been compression-bonded temporarily in the first compression bonding unit 9, are subjected to a main compression bonding for the matrix substrate 3 as a second step, as shown in FIG. 9. In the main compression bonding, a high pressure is fed to the space 10 p from the air supply system 10 q in the block body portion 10 d to pressurize each pressure block 10 n at a desired preset load, and, at the same time, the semiconductor chips are heated directly by the second heating stage 10 b.

More specifically, in the second compression bonding unit 10, plural (for example, three in FIG. 9) semiconductor chips 1 are heated and pressurized at one time (simultaneously). The pressurizing time for one semiconductor chip 1 in the second compression bonding unit 10 is, for example, 4 seconds or so and is thus much longer than in the first compression bonding unit 9.

As shown in FIG. 11, a load cell 10 e operating as a load change detecting means is incorporated in the second head 10 a to detect the total load imposed on each semiconductor chip in actual thermocompression bonding and the landing height of the head tip (the front end portion of each pressure block 10 n).

The load cell 10 e is disposed on a load cell support portion 10 h and is supported in a sandwiched state between the load cell support portion 10 h and a height control plate 10 f. According to this structure, the weight of the front end-side block beyond the load cell 10 e can be cancelled. The height control plate 10 f can control the height with use of a servo-motor 10 g. The load cell support portion 10 h is connected to the block body portion 10 d through the inclination adjusting mechanism 10 i which is used for adjusting the inclination of the block body portion 10 d.

The height of the second heating stage 10 b can also be servo-controlled.

In the second head 10 a, the load control can be carried out by using only the front-end pressure of the head. More particularly, the load imposed on the plural pressure blocks 10 n can be switched from one to another value by controlling the amount of air fed into the space 10 p from the air supply system 10 q in the block body portion 10 d.

With such a load control, at the time of thermocompression bonding in the second compression bonding unit 10, the plural pressure blocks 10 n can be made to land at a low load relative to the products, as shown in FIG. 12A at stages A to D.

More specifically, the matrix substrate 3 g after temporary compression bonding of the semiconductor chips 1 on the first heating stage 9 b in the first compression bonding unit 9 is then disposed on the second heating stage 10 b in the second compression bonding unit 10 which is adjacent to the first compression bonding unit 9. At this time, the semiconductor chips 1 are disposed on the lower side of the matrix substrate 3 g, i.e., on the second heating stage 10 b side, and air at a low pressure (first pressure) is fed into the space 10 p from the air supply system 10 q in the block body portion 10 d and is applied to the plural pressure blocks 10 n (FIG. 12 at A).

In this state, the second heating stage 10 b is raised, allowing plural semiconductor chips 1 to be placed on the second heating stage 10 b (FIG. 12 at B). Since the heater 10 c is incorporated in the second heating stage 10 b, the plural semiconductor chips 1 are heated directly by the second heating stage 10 b.

Thereafter, the second head 10 a is moved down, whereby the plural pressure blocks 10 n each supported for independent movement by the support blocks portion 10 m are brought into contact with the matrix substrate 3 g (FIG. 12 at C).

After the matrix substrate 3 g and the plural semiconductor chips 1 have been sandwiched in between the second heating stage 10 b and the plural pressure blocks 10 n, air of a higher pressure (second pressure) than the foregoing low pressure (first pressure) is fed into the space 10 p from the air supply system 10 q in the block body portion 10 d and is applied to the pressure blocks 10 n (FIG. 12 at D).

In this case, after all the pressure blocks 10 n have landed at a small load onto the matrix substrate 3 g, variations in height of the pressure blocks 10 n are absorbed by the elastic film 10 t and, in this state, switching to the high pressure is effected.

In this state, on the second heating stage 10 b in the second compression bonding unit, a main compression bonding is carried out as thermocompression bonding between the matrix substrate 3 g and the plural semiconductor chips 1, while heating the plural semiconductor chips 1 by use of the second heating stage 10 b.

That is, at the time of carrying out the main compression bonding in the second head 10 a according to this embodiment, a low load is applied to the matrix substrate 3 g until contact of the plural pressure blocks 10 n with the products. Then, after the contact, switching is to the high pressure is carried out and the original set pressure is applied to both matrix substrate 3 g and the semiconductor chips 1. By so doing, at the time of landing of the head in the main compression bonding, products can be prevented from being shocked and damaged by the pressure blocks 10 n.

The semiconductor chips 1 are pressurized by the second head 10 a in the second compression bonding unit 10 for a longer time than the pressurizing time in the first heating stage 9 b. For example, the pressuring time in the first heating stage 9 b is about 0.1 second, while the pressurizing time in the second heating stage is about 4 seconds. Since the semiconductor chips 1 can thus be pressurized for a relatively long time in the second heating stage 10 b, the product heating time can be set relatively low in comparison with that in the conventional die bonding method.

FIG. 13 illustrates a modification of the chip mounting method shown in FIG. 12. In FIG. 13, the matrix substrate 3 g and the semiconductor chips 1, which have been compression-bonded temporarily in the first heating stage 9 b, are disposed on the second heating stage 10 b (FIG. 13 at A), and then the second head 10 a is moved down, causing the plural pressure blocks 10 n to come into contact with the matrix substrate 3 g (FIG. 13 at B). Thereafter, the second heating stage 10 b is raised, whereby the matrix substrate 3 g and the semiconductor chips 1 are sandwiched in between the pressure blocks 10 n and the second heating stage 10 b (FIG. 13 at C). These operations are performed at a low pressure as is the case with the chip mounting method shown in FIG. 12.

Thereafter, in the same manner as in the chip mounting method shown in FIG. 12, air of a higher pressure (second pressure) than the above-mentioned low pressure (first pressure) is fed into the space 10 p from the air supply system 10 q in the block body portion 10 d and is applied to the plural pressure blocks 10 n. In this state, a main compression bonding is performed (FIG. 13 at D).

When the main compression bonding is to be performed in the second compression bonding unit 10, the semiconductor chips 1 disposed on the lower side of the matrix substrate 3 g are heated directly from their back surfaces (second main surfaces) 1 c on the second heating stage 10 b without interposition of the substrate; and, at the same time, the matrix substrate 3 g is heated through the support block portion 10 m and pressure blocks 10 n by means of the heater 10 c incorporated in the block body portion 10 d which is disposed above. In this way the matrix substrate 3 g and the bonding portions of the semiconductor chips 1 are thermocompression-bonded to each other while being heated from both upper and lower sides.

That is, the semiconductor chips 1 are heated from the second heating stage 10 b side, while the matrix substrate 3 g is heated from the side opposite to the second heating stage 10 b with respect to the matrix substrate, to effect thermocompression bonding.

At this time, the semiconductor chip side is heated at a higher temperature than on the substrate side. For example, since the semiconductor chip 1 is formed of silicon and is relatively high in thermal conductivity, the semiconductor chip side is heated at a temperature of about 200° C. On the other hand, the matrix substrate 3 g is mainly formed of an insulating material, and so it is poor in thermal conductivity and is apt to cause thermal deformation and breaking of the wire. Therefore, for the matrix substrate 3 g side, there is set as low a temperature as possible, e.g., 150° C. or lower, 100° C. or lower, if possible, preferably 50° C. or lower, most suitably a normal temperature.

Reference will now be made to a structural example of the matrix substrate 3 g (organic substrate 3). An organic resin serving as a base which constitutes a principal portion of the matrix substrate is made, for example, of BT resin (bismaleimide triazine resin) and wiring copper layers are formed respectively on both the top surface and back surface of the organic resin base. Further, a solder resist film, which is an organic insulating film (organic layer), is formed on the surface of a predetermined area in each of the wiring layers. Thus, the matrix substrate 3 g (organic substrate 3) is a multi-layer wiring substrate having two wiring layers.

The glass transition temperature (Tg) of the BT resin is, for example, 240° to 330° C. In this case, therefore, the heating temperature (200° C.) from the back surface 1 c side of the semiconductor chips 1 on the second heating stage 10 b is lower than the glass transition temperature (240° to 330° C.) of the BT resin, and, thus, it is possible to prevent the occurrence of an inconvenience caused by heat, such as thermal deformation of the substrate.

The modulus of rigidity of the solder resist film is lower than that of BT resin as the organic resin base, and thus the bonding between the semiconductor chips 1 and the matrix substrate 3 g (organic substrate 3) is performed through the solder resist film, which is an organic layer lower in rigidity modulus than BT resin. Consequently, it is possible to enhance the adhesion between the semiconductor chips 1 and the substrate.

The structure of the matrix substrate 3 g is not limited to the above-described structure. For example, it may be a multi-layer wiring substrate having two or more wiring layers. The organic resin base which constitutes the foregoing principal portion of the substrate may be any other resin than BT resin.

Further, the bonding between the semiconductor chips 1 and the adhesive, such as the die bonding tapes 2, is a bonding between surfaces, i.e., main surfaces 1 b of the semiconductor chips 1, and the adhesive. For example, when a protective film is formed on the surface of each semiconductor chip 1, the protective film and the adhesive are bonded, i.e., thermocompression-bonded, to each other.

FIG. 14 illustrates the detecting of landing of the front end of the second head 10 a relative to the pressure blocks 10 n. For detecting the landing referred to, first, with products not placed on the second heating stage 10 b, a high pressure, which is high to such an extent as to not push up the pressure blocks 10 n, is applied from the air supply system 10 q in the block body portion 10 d to the plural pressure blocks 10 n, each of which are supported for independent movement by the support block portion 10 m. That is, a high pressure is applied to the pressure blocks 10 n in such a manner that the pressure blocks 10 n are not forced up at an ordinary load.

In this state, the second heating stage 10 b is raised into contact with the plural pressure blocks 10 n. Further, the motor 10 g is turned ON to let the control plate 10 f move down. In this case, the position at which the load cell 10 e indicates a change corresponds to an initial height of the pressure blocks 10 n. According to this method, it is possible to determine the landing height of the pressure blocks 10 n.

Further, with products placed on the second heating stage 10 b, the pressure to be applied to the pressure blocks 10 n is raised gradually from a low level and a point of change of the load imposed on the load cell 10 e is detected, whereby the magnitude of pressure imposed on plural semiconductor chips 1 can be determined. That is, while the semiconductor chips 1 are actually subjected to the main compression bonding, it is possible to determine the magnitude of pressure imposed on the semiconductor chips.

FIG. 15 illustrates the detecting of a set load.

More specifically, with products not placed on the second heating stage 10 b, first the second heating stage 10 b is raised while applying a low pressure to the pressure blocks 10 n, causing the pressure blocks 10 n and the second heating stage 10 b to come into contact with each other. That is, the pressure blocks 10 n are kept in a landed state with a low pressure. In this state, the height control plate 10 f is moved down a predetermined certain distance by operating the motor 10 g to push in the load cell 10 e.

Thereafter, the pressure applied to the plural pressure blocks 10 n is raised gradually and a point of change of the load imposed on the load cell 10 e is detected, whereby it is possible to determine the magnitude of a set value of pressure which is imposed on the plural pressure blocks 10 n at the time of performing the thermocompression bonding (main compression bonding) with the semiconductor chips 1 disposed on the second heating stage 10 b.

In this way, with the chip mounter 8 alone, it is possible to detect the magnitude of a set load at the time of thermocompression-bonding plural semiconductor chips 1 at one time.

After detection of the set load upon arrival at the load, the set air pressure is stored in the chip mounter 8.

FIG. 16 illustrates a tool changing method.

In the chip mounter 8 according to this embodiment, in the second head 10 a, the support block portion 10 m (also called a tool) which supports the pressure blocks 10 n is mounted to the block body portion 10 d removably, and by removing and replacing only the support block portion 10 m (only the tool), it is possible to easily cope with a change of type, e.g., a change in the number of semiconductor chips 1, the chip size or the load.

FIG. 17 shows the magnitude of a load imposed on each pressure block 10 n and how to absorb variations in height of the pressure blocks 10 n. The magnitude of a load imposed on each pressure block 10 n is equal to the air pressure P×the pressure receiving area S. At a low pressure, the elastic film 10 t is deformed so as to follow the head shape of the pressure blocks 10 n so as to absorb any error in height of each pressure block 10 n, followed by adjustment to the set pressure. As a result, it is possible to absorb variations in height of the pressure blocks 10 n.

FIG. 18 shows how to prevent the generation of silicon waste (dust particles) in the second heating stage 10 b and how to prevent inclusion of the waste.

On the surface of the second heating stage 10 b there are plural small-sized stages 10 j which are each smaller than the back surface (second main surface) 1 c of each semiconductor chip 1. With such small-sized stages 10 j, when each semiconductor chip 1 is placed on each small-sized stage 10 j, end portions of the back surface 1 c of the semiconductor chip 1 do not contact the small-sized stage 10 j, nor do they contact chipping start positions by dicing of the semiconductor chip 1. Consequently, it is possible to prevent the generation of silicon waste.

In the second heating stage 10 b there are plural suction systems 10 k which are open to the chip-side face. Dust particles, such as silicon waste that has fallen off onto the chip-side face during the main thermocompression bonding of the semiconductor chips 1 and the matrix substrate 3 g, can be sucked in and removed through the suction systems 10 k.

Thus, even in the event of generation of dust particles, such as silicon waste, they can be removed through the suction systems 10 k, so that it is possible to prevent the inclusion of dust particles between the semiconductor chips 1 and the stage.

FIG. 19 shows the appearance of the structure of the support block portion 10 m when mounted to the block body portion 10 d. As shown in FIG. 20, the support block portion 10 m is brought into sliding fit in the lower portion of the block body portion 10 d and is fixed using a fixing screw 10 w.

As shown in FIG. 21, the support block portion 10 m is formed in a recessed shape, and through holes 10 x in a number corresponding to the number of the pressure blocks 10 n are formed in the bottom of the support block portion 10 m. As shown in FIG. 22, each pressure block 10 n has a projection shape and functions as a plunger. The projection portions of the pressure blocks 10 n are positioned respectively in the through holes 10 x formed in the bottom of the support block portion 10 m. According to this arrangement, front end portions of the pressure blocks 10 n slightly project downward from the support block portion 10 m.

Within the support block portion 10 m, as shown in FIG. 21, a sheet-like elastic film 10 t is disposed on the pressure blocks 10 n; then, a frame-like elastic spacer 10 s is disposed on the elastic film 10 t; and, further, a frame-like metallic spacer 10 r is disposed at the top stage.

As shown in FIG. 22, the support block portion 10 m is mounted to the block body portion 10 d in a removable manner.

The frame-like elastic spacer 10 s is formed of a fluorine-based rubber, for example, and it seals the space 10 p hermetically to prevent the leakage of vacuum. Further, with the elastic force of the elastic spacer 10 s, it is possible to stabilize the load at peripheral edge portions of the plural pressure blocks 10 n.

The metallic spacer 10 r is formed of stainless steel, for example, and it functions to prevent galling and sticking as close contact of the elastic spacer 10 s to the block body portion 10 d, thereby facilitating mounting and removal of the support block portion 10 m to and from the block body portion 10 d. That is, the support block portion 10 m is removably mounted relative to the block body portion 10 d through the metallic spacer 10 r.

The elastic film 10 t is a sheet-like member formed of a fluorine-based rubber, for example, having a thickness of about 0.5 mm. When air pressure is applied to the space 10 p, the elastic film 10 t pressurizes the head portions of the pressure blocks 10 n simultaneously. Since the elastic film 10 t is very thin, it can move so as to follow vertical movements of each individual pressure block 10 n.

As shown in FIG. 22, an air supply system 10 q communicating with the space 10 p is formed in the block body portion 10 d to which the support block portion 10 m is attached, and a relay pipe (air introducing portion) 10 u for introducing air into the air supply system 10 q is attached to the block body portion 10 d. A hose 10 v is connected to the relay pipe 10 u and air under pressure is fed to the air supply system 10 q through the hose 10 v and further through the relay pipe 10 u.

Thus, it is preferable that the relay pipe 10 u be long to such an extent that is does not conduct heat to the hose 10 v. if the relay pipe 10 u is short, heat is conducted to the hose 10 v, with consequent expansion of the hose 10 v and a change in the amount of air. Therefore, it is preferable to make the relay pipe 10 u long so as not to cause a change in the amount of air being fed and to enhance the heat resistance of the pipe.

FIG. 23 shows various structures for stabilizing the load in the support block portion 10 m. In this figure there are illustrated a structure wherein the elastic film 10 t is thinned by seal thinning to enhance the responsivity of the elastic film, a structure wherein the elastic film 10 t is made into a diaphragm type by rise thinning, a structure wherein a gap is formed between adjacent pressure blocks 10 n by plunger pitch expansion, and a structure wherein deflections are ensured in the elastic film 10 t at positions each corresponding to locations between adjacent pressure blocks 10 n by a seal buffer mechanism to make motions of the pressure blocks 10 n difficult to be mutually influenced.

In the semiconductor integrated circuit device fabricating method according to this embodiment, die bonding is carried out in a divided manner using the first heating stage 9 b and the second heating stage 10 b. Temporary bonding (temporary compression bonding) is performed in a short time in the first heating stage 9 b; and, thereafter, plural semiconductor chips 1 are subjected to a main bonding (main compression bonding) in the second heating stage 10 b, whereby it is possible to shorten the bonding time.

Consequently, it is possible to improve the throughput of die bonding and, hence, to improve the productivity thereof.

Moreover, since the application of pressure can be carried out over a relatively long time in the second heating stage 10 b, the heating temperature can be set lower than in the conventional die bonding method.

As a result, in the case where the matrix substrate 3 g is an organic substrate having wires 3 d, it is possible to diminish deformations, such as warping of the organic substrate, and it is also possible to diminish the occurrence of defects, such as peel-off of wiring patterns.

More particularly, in an organic substrate, a solder resist film serving as an insulating film (organic layer) on the substrate surface and copper wires are markedly different in thermal expansion coefficient from each other; and, if the heating temperature is high, peeling of wiring patterns and substrate deformation caused by such a difference in thermal expansion coefficient are apt to occur. In this embodiment, however, since the heating temperature can be set low, it is possible to diminish the occurrence of the aforesaid defects of the organic substrate. Further, since substrate deformation can be diminished, it is possible to stabilize the adhesion between the substrate and the semiconductor chips 1.

In the conventional bonding of a wiring substrate and semiconductor chips 1 by flip-chip connection, the semiconductor wafers 1 are picked up from a semiconductor wafer and are placed on the substrate such that their main surfaces 1 b face toward the substrate, and then the semiconductor chips 1 and the wiring substrate are bonded together by thermocompression bonding, for example. In this case, a conveyance mechanism for conveying the semiconductor chips 1 onto the substrate is disposed above the wiring substrate. Since the conveyance mechanism is thus disposed above the wiring substrate, it is difficult to dispose a heating mechanism above the substrate and, therefore, it is embedded in a stage located below the wiring substrate. When heating is conducted from the stage side in this structure, the chip-substrate bonding portions are heated through the substrate, so that the temperature of the bonding portions does not rise to a satisfactory extent and insufficient bonding results. Further, if the heating temperature is raised in an effort to ensure a sufficient temperature of the bonding portions, the wiring substrate may undergo a deformation, such as warping, or there may occur peeling of the compression-bonded portions.

In contrast therewith, in the semiconductor integrated circuit device fabricating method according to this embodiment, when die bonding is to be conducted, the semiconductor chips 1 are disposed on a heating stage such that their main surfaces 1 b face upward, and the matrix substrate 3 g is disposed above the semiconductor chips 1. Then, then in this state, both are bonded together. Therefore, the back surfaces 1 c of the semiconductor chips 1 can be heated directly without interposition of the substrate, whereby the chips can be heated efficiently. As a result, not only can the bonding portions between the semiconductor chips 1 and the matrix substrate 3 g can be heated to a satisfactory extent, but also the heating temperature from the substrate side can be set lower than on the chip side. Consequently, it is possible to diminish a thermal deformation of the wiring substrate.

Further, since the bonding portions between the semiconductor chips and the wiring substrate can be heated to a satisfactory extent, it is possible to stabilize the bonding of the semiconductor chips 1. Accordingly, it is possible to prevent the occurrence of such inconveniences as peel-off of the bonded portions (compression-bonded portions), and it is possible to stabilize the bonding quality of the semiconductor chips. Hence, it is possible to improve the reliability of the products obtained.

In the case of using thinned semiconductor chips 1 with thinning of the semiconductor integrated circuit device, such as BOC 7, the use of a chip inverting mechanism is needed in the bonding between the wiring substrate and the semiconductor chips 1 by the conventional flip-chip connection, and it becomes difficult to handle thinned chips. Consequently, inconveniences are apt to occur at the time of inverting the chips.

In contrast therewith, in the semiconductor integrated circuit device fabricating method according to this embodiment, the semiconductor chips 1 are placed on the stage so that their main surfaces 1 b face upward without using the chip inverting mechanism. Thus, since the chip inverting mechanism becomes unnecessary, the structure of the semiconductor device manufacturing apparatus can be so much simplified. Besides, since the semiconductor chips 1 are heated on the stage directly from their back surfaces 1 c side without interposition of the substrate, the bonding portions between the semiconductor chips and the wiring substrate can be heated more efficiently corresponding to the thinning of the semiconductor chips 1.

Although the present invention has been described above by way of embodiments thereof, it goes without saying that the invention is not limited to the above-described embodiments, but that various changes may be made within a scope not departing from the gist of the invention.

For example, although in the above-description of the embodiments reference has been made to BOC 7 as an example of the semiconductor integrated circuit device, the semiconductor device is not limited to the BOC 7 insofar as the semiconductor device used is assembled by bonding a semiconductor chip 1 and a substrate, such as the matrix substrate 3 g, to each other.

The semiconductor device may be, for example, an LOC (Lead On Chip) 20 such as shown in FIG. 24. In the LOC 20, inner leads 20 a and a semiconductor chip 1 are bonded together through die bonding tapes 2. The inner leads 20 a and the semiconductor chip 1 are electrically connected with each other through wires 4 while straddling bus bar leads 20 c. Further, outer leads 20 b are formed in a gull wing shape.

In assembling the LOC 20, the semiconductor integrated circuit device fabricating method according to this embodiment is applied at the time of bonding the semiconductor chip and a lead frame (substrate) having the inner leads 20 a and the outer leads 20 b.

The present invention is suitable for its application to a semiconductor integrated circuit device fabricating technique involving the bonding of a substrate and semiconductor chips to each other. 

1. A method of fabricating a semiconductor integrated circuit device, comprising the steps of: (a) providing a substrate; (b) disposing a plurality of semiconductor chips over a stage in such a manner that respective main surfaces face upward; (c) disposing the substrate above the plural semiconductor chips; and (d) bonding the plural semiconductor chips all together to the substrate by thermocompression bonding.
 2. A method according to claim 1, wherein an organic wiring substrate is used as the substrate.
 3. A method of fabricating a semiconductor integrated circuit device, comprising the steps of: (a) providing a substrate; (b) disposing a plurality of semiconductor chips over a stage; (c) disposing the substrate over first main surface sides of the plural semiconductor chips; and (d) pressurizing the plural semiconductor chips correspondingly by a plurality of pressure blocks while heating the semiconductor chips from second main surface sides of the chips by the stage, the plural pressure blocks being supported each independently movably in corresponding relation to the semiconductor chips, thereby thermocompression bonding the semiconductor chips all together to the substrate.
 4. A method according to claim 3, wherein the heating in the step (d) is performed also from the first main surface sides of the semiconductor chips.
 5. A method according to claim 3, wherein the heating from the second main surface sides of the semiconductor chips is performed directly without interposition of the substrate.
 6. A method according to claim 3, wherein the substrate is an organic wiring substrate.
 7. A method according to claim 6, wherein the temperature of the heating from the second main surface sides of the semiconductor chips is lower than the glass transition temperature of an organic resin which constitutes a principal portion of the organic wiring substrate.
 8. A method of fabricating a semiconductor integrated circuit device, comprising the steps of: (a) providing a substrate; (b) disposing a plurality of semiconductor chips over a stage; (c) disposing the substrate above the semiconductor chips; and (d) heating the semiconductor chips from the stage side and heating the substrate from the side opposite to the stage in such a manner that the heating temperature at the semiconductor chip side is higher than that at the substrate side.
 9. A method according to claim 8, wherein the substrate is heated at a temperature of not higher than 150° C.
 10. A method according to claim 8, wherein the substrate is heated at a temperature of not higher than 100° C.
 11. A method according to claim 8, wherein the substrate is heated at a temperature of not higher than 50° C.
 12. A method according to claim 8, wherein the substrate is heated at a normal temperature.
 13. A method according to claim 8, wherein an organic wiring substrate is used as the substrate. 